1. Field of the Invention
The present invention relates to a method of monitoring the status of a plasma processing system and, more particularly, to a method and system for monitoring the status of a plasma processing system using a pressure control system.
2. Description of Related Art
The fabrication of integrated circuits (IC) in the semiconductor industry typically employs plasma to create and assist surface chemistry within a plasma processing system necessary to remove material from and deposit material to a substrate. In general, plasma is formed within the plasma processing system under vacuum conditions by heating electrons to energies sufficient to sustain ionizing collisions with a supplied process gas. Moreover, the heated electrons can have energy sufficient to sustain dissociative collisions, and therefore, a specific set of gases under predetermined conditions (e.g., chamber pressure, gas flow rate, etc.) are chosen to produce a population of charged species and chemically reactive species suitable to the particular process being performed within the chamber (e.g., etching processes where materials are removed from the substrate or deposition processes where materials are added to the substrate).
The processes described above are sensitive to the conditions achieved within the plasma processing system and, in order to meet expected yields, precise control of these conditions is now required. For example, changes in these conditions due to either abrupt changes (or faults), or gradual changes require constant monitoring. Therefore, it is of increasing importance to detect fault conditions, determine whether the fault is real or erroneous, and determine if a service condition is present.